/*
 * ------------------------------------------------------------------------
 *
 *  Copyright by KNIME AG, Zurich, Switzerland
 *  Website: http://www.knime.com; Email: contact@knime.com
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License, Version 3, as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses>.
 *
 *  Additional permission under GNU GPL version 3 section 7:
 *
 *  KNIME interoperates with ECLIPSE solely via ECLIPSE's plug-in APIs.
 *  Hence, KNIME and ECLIPSE are both independent programs and are not
 *  derived from each other. Should, however, the interpretation of the
 *  GNU GPL Version 3 ("License") under any applicable laws result in
 *  KNIME and ECLIPSE being a combined program, KNIME AG herewith grants
 *  you the additional permission to use and propagate KNIME together with
 *  ECLIPSE with only the license terms in place for ECLIPSE applying to
 *  ECLIPSE and the GNU GPL Version 3 applying for KNIME, provided the
 *  license terms of ECLIPSE themselves allow for the respective use and
 *  propagation of ECLIPSE together with KNIME.
 *
 *  Additional permission relating to nodes for KNIME that extend the Node
 *  Extension (and in particular that are based on subclasses of NodeModel,
 *  NodeDialog, and NodeView) and that only interoperate with KNIME through
 *  standard APIs ("Nodes"):
 *  Nodes are deemed to be separate and independent programs and to not be
 *  covered works.  Notwithstanding anything to the contrary in the
 *  License, the License does not apply to Nodes, you are not required to
 *  license Nodes under the License, and you are granted a license to
 *  prepare and propagate Nodes, in each case even if such Nodes are
 *  propagated with or for interoperation with KNIME.  The owner of a Node
 *  may freely choose the license terms applicable to such Node, including
 *  when such Node is propagated with or for interoperation with KNIME.
 * ---------------------------------------------------------------------
 *
 * History
 *   Oct 15, 2020 (Adrian Nembach, KNIME GmbH, Konstanz, Germany): created
 */
package org.knime.filehandling.core.node.table.reader.selector;

import org.knime.filehandling.core.node.table.reader.spec.TypedReaderTableSpec;

/**
 * Enum of column filter modes specifying how new columns are to be handled.
 *
 * @author Adrian Nembach, KNIME GmbH, Konstanz, Germany
 */
public enum ColumnFilterMode {
        /**
         * All columns in the union of tables are kept. That is if a column is present in any file, it is part of the
         * output table.
         */
        UNION() {

            @Override
            public <T> TypedReaderTableSpec<T> getRelevantSpec(final RawSpec<T> spec) {
                return spec.getUnion();
            }

        },
        /**
         * All columns that are contained in all tables are kept. That means a column is kept only if it is present in
         * all files.
         */
        INTERSECTION() {

            @Override
            public <T> TypedReaderTableSpec<T> getRelevantSpec(final RawSpec<T> spec) {
                return spec.getIntersection();
            }

        };

    /**
     * Returns the {@link TypedReaderTableSpec} contained in {@link RawSpec} that is relevant for this
     * {@link ColumnFilterMode}.
     *
     * @param <T> the type used to identify external data types
     * @param rawSpec {@link RawSpec} from which to extract the relevant {@link TypedReaderTableSpec}
     * @return the relevant {@link TypedReaderTableSpec} extracted from {@link RawSpec rawSpec}
     */
    public abstract <T> TypedReaderTableSpec<T> getRelevantSpec(final RawSpec<T> rawSpec);
}